FLAVONOID NATURAL SOURCES AND THEIR IMPORTANCE IN THE HUMAN DIET

Abstract

Flavonoids as natural bioactive compounds are present in almost every sort of fruits, vegetables and from them derived products. Flavonols may be found mainly in fruits and vegetables, while flavones are abundant in herbs and spices. Rich natural sources of flavanols are tea, cocoa, grape seeds or apple skin. Flavanones are primarily found in a variety of citrus fruits and anthocyanidins in many coloured berries. Soy is rich in isoflavonoids. Average daily intake of flavonoids is approximately in the range of 150 to 300 mg. It strongly depends on individual, country and culture usages. In west countries main dietary sources of flavonoids consist of tea, wine and fruits, while in east countries there is consumed mainly soy with high isoflavonoid content. Many studies have shown, that intake of fruits and vegetables with high flavonoid content is associated with lowered risk of incidence of some diseases such as cardiovascular or cancer. These findings are attributed to experimentally confirmed biological effects of flavonoids - antioxidant, anti-inflammatory, anti-allergic, anticancer or cardioprotective. The final effect is however depending on their bioavailability, which is in the case of flavonoids not high, because in the nature dominating flavonoid glycosides can poorly penetrate through lipophilic cell membranes. Final effective molecules are flavonoid metabolites, that more or less retain their biological activities. doi: 10.5219/160

Keywords

• bioavailability
• biological effect
• daily intake
• flavonoid
• natural source